Introduction
Ureteral strictures may arise from a multitude of etiologies including ischemia, iatrogenic trauma, noniatrogenic trauma, retroperitoneal fibrosis (RPF), radiation, malignancy, or ureteral calculi. Surgical reconstruction is necessary to preserve renal function due to the risk of prolonged hydronephrosis as well as symptomatic relief in those who have flank pain. Robotic reconstruction has been proven to be feasible with outcomes equivalent, if not better, than that of traditional open and laparoscopic procedures.
Proximal ureter
The proximal ureter, radiologically, is defined to be the segment of the ureter between the renal pelvis and the superior border of the sacroiliac joint. Some texts include the ureteropelvic junction (UPJ) within the proximal ureter; however, for the purposes of this chapter, the proximal ureter and UPJ will be considered two distinct entities, and thus pyeloplasty will not be discussed here as it has been a well-established surgery for UPJ obstruction. The proximal ureteral blood supply arises medial-to-lateral, mostly from the main renal artery with some contribution from smaller branches directly off the aorta as well as the gonadal artery. Thus, when performing an endopyelotomy for proximal ureteral strictures, the incision should be made laterally to minimize ureteric ischemia.
The more proximal the ureter, the more robust the vascularity, as it is closer to the branches from the main renal artery. This is one of the reasons why pyeloplasty outcomes are excellent. However, following the proximal ureter down caudally, the arterial plexus overlying the ureter becomes more tenuous before it meets another arterial plexus originating from branches off the gonadal artery or directly off the aorta. In other words, there are watershed regions of the proximal ureter, which makes strictures in this location more difficult to manage. Surgical dissection of the proximal ureter must be precise with care to leave as much adventitia on the ureter as possible and to avoid lateralizing the ureter extensively. Following those surgical principles in the proximal ureter decreases the risk of ischemia to the ureteral repair and subsequently decreases the risk of stricture recurrence.
Mid-ureter
The mid-ureter, radiologically, is defined to be the segment of the ureter between the superior border of the sacroiliac joint and the inferior border of the sacroiliac joint, or more simply, the pelvic inlet. This segment obtains its vascularity from posterior to anterior originating off the common iliac artery.
Distal ureter
The distal ureter, radiologically, is defined to be the segment of the ureter between the pelvic inlet and the ureterovesical junction. Its blood supply comes from lateral-to-medial from branches off the internal iliac artery and larger internal iliac artery branches (e.g., superior vesical, uterine, inferior vesical, middle rectal, etc.). Despite these multiple plexuses, ureteral vascularity is still tenuous. Blood supply to the bladder will almost always be superior to that of the distal ureter; thus, when managing distal ureteral strictures, ureteroneocystostomy/ureteral reimplantation is the reconstructive technique of choice.
Ureteral identification and dissection
The retroperitoneum must be adequately visualized prior to identifying the ureter. In proximal- and mid-ureteral strictures, the colon should be reflected medially by incising the white line of Toldt in order to expose the retroperitoneum underneath. On right-sided procedures, the Kocher maneuver may need to be performed in order to medialize the duodenum in order to visualize the hilar strictures of the kidney, including the gonadal vessels, which does aid in the identification of the ureter. In distal-ureteral strictures, depending on the adhesions of the bowel to the pelvic sidewall, retraction of bowel medially may be enough to adequately visualize the shape and pulsation of the iliac vessels, which is a good landmark for where to start looking for the ureter, which crosses the iliac vessels at the bifurcation of the common iliac into the external and internal iliac vessels.
In certain cases where there may be strong fibrotic or desmoplastic reactions in the retroperitoneum, finding the ureter may be particularly challenging. A fibrotic rind may encase the ureter and distort the normal expected location of the ureter (e.g., RPF medializing the ureter). In these cases, it is advantageous to identify the normal ureter either proximal or distal to the diseased segment and to follow it from known to unknown, as a surgical principle.
Should anatomic considerations be inadequate in identifying the ureter, there are some adjunctive techniques that may help. If the patient already has an indwelling ureteral stent in place, an ultrasound probe may prove to be useful in identifying the stent; using the same logic, if a patient does not have a preexisting indwelling ureteral stent, an open-ended ureteral catheter may be placed intraoperatively in order to assist in ultrasonographic identification. Ureteroscopy is very helpful when performing ureteral reconstruction, as it allows for correlation between the intraluminal status of the ureter with the extraluminal appearance robotically. The latest robotic console software includes a near-infrared imaging (NIRF) modality. Ureteroscopy comes in handy with the utilization of NIRF, as the light emanating from the ureteroscope is enhanced in NIRF, allowing for identification of the ureter. One adjunct that has been increasingly popular is the use of intraureteral indocyanine green (ICG). Five mL of diluted ICG can be instilled either retrograde via cystoscopy with ureteral catheterization or antegrade via an existing nephrostomy tube. ICG binds to the tissues of the ureter and is fluorescent green in the NIRF setting. ICG has also been commonly used intravenously (2 mL) to assess for tissue perfusion ( Fig. 33.1 ). Thus, the downside to utilizing intraureteral ICG for ureteral identification is that the option to use it intravenously to assess for ureteral vascularity becomes confounded. Because of this, if the ureter can be identified without using intraureteral ICG, it may be advantageous to save the ICG to be used intravenously in order to ensure the reconstructed segment of ureter is adequately perfused.
After the ureter has been identified, it needs to be isolated. The anterior aspect of the retroperitoneum overlying the ureter should be incised into until the adventitia is visualized, with judicious electrocautery use to minimize ischemia. While the anterior ureter is generally safe to dissect out, a surgeon may choose to hedge toward one side or the other based on the diseased segment location; as mentioned previously, the proximal ureter obtains its arterial branches medially and thus dissecting anterolaterally may preserve more blood supply while the distal ureter obtains its arterial branches laterally and dissecting anteromedially may be beneficial in the pelvis. Usually, circumferential isolation of the ureter is performed, but depending on the etiology of stricture, it may not be needed. If there is concern that extraluminal tissue is contributing to the ureteral stricture (e.g., RPF), circumferential isolation should definitely be performed. If an omental wrap needs to be performed (e.g., buccal mucosal ureteroplasty, ureterolysis), getting completely around the ureter is needed. However, in circumstances where ureteral dissection is tough and may compromise the adventitia and its vascular plexus, and the surgeon is able to reconstruct the ureter without complete ureteral transection (e.g., appendiceal bypass or side-to-side reimplantation), circumferential isolation may not be needed.
Finally, one important aspect of ureteral identification and dissection is discerning healthy tissue versus unhealthy tissue. A reconstructive surgical principle is to trim or exclude unhealthy tissue until a viable ureter is seen so that an anastomosis will have optimal perfusion for healing. An unhealthy ureter is generally pale or discolored with minimal to no bleeding when cutting into it. If there is any question about the viability of tissues, 2 mL intravenous ICG, as mentioned above, is an excellent modality to assess for tissue perfusion.
Ureteral rest
An emerging concept that has been extrapolated from a universally accepted urethral reconstructive principle is ureteral rest. Defined as the absence from ureteral instrumentation for a prolonged period of time leading up to the operation, ureteral rest has been proven to be beneficial in ureteral reconstructive outcomes. A recent multi-institutional retrospective study of 234 patients showed that those who had no indwelling ureteral stent or percutaneous nephroureteral tube for at least 4 weeks prior to surgery had a 90.7% success rate versus 77.5% in those without ureteral rest ( P = .057), with fewer patients needing to undergo buccal mucosa graft ureteroplasty. The hypothesized physiology behind ureteral rest is tissue recovery and maturation of the stricture, as recent instrumentation and/or continued hardware (indwelling ureteral stent or nephroureteral tube) alters stricture characteristics with more periureteral inflammation, making surgery more technically difficult and tissue healing less effective.
Ureterolysis
Retroperitoneal fibrosis
Ureterolysis is a procedure reserved to manage patients who have ureteral obstruction secondary to extrinsic compression. Causes may include tumors, infection, and, most commonly, RPF. RPF is a process characterized by fibrosis and chronic retroperitoneal inflammation, usually originating from periaortic and other great vessels’ adventitia. RPF is a general term, with some of its causes including endovascular stents (for abdominal aortic aneurysms, for example), spinal hardware, prior retroperitoneal surgery, radiation, medication adverse effects especially that of ergot alkaloids (such as methysergide), and other processes that recruit inflammatory reactions affecting the retroperitoneum. Thus, RPF is not to be confused with idiopathic RPF, which, as its name suggests, is an inflammatory process unable to be attributed to as secondary to an inciting event. While rare, with an incidence of 0.1 to 1.3 cases/100,000 people annually, idiopathic RPF is thought to have an etiology from disease processes on the spectrum of autoimmune disorders such as large vessel vasculitides. Over the past decade, a relationship to IgG4 has been described, with its pathophysiology hypothesized to be a lymphoplasmacytic, fibrotic, and IgG4+ plasma cell infiltration of various organ systems. It is associated with other autoimmune disorders such as rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, and, most commonly, thyroiditis.
The most common sequelae of RPF is ureteral involvement which can be bilateral or unilateral. At the time of diagnosis of unilateral disease, the contralateral side can be affected gradually between weeks to years, albeit rare. Multiple studies have shown that the risk of contralateral obstruction is low, and thus, bilateral ureterolysis for unilateral disease is not required. Classically, the mid to proximal ureter is affected, extrinsically compressed and deviated medially.
Prior to surgical intervention, the etiology of RPF should be determined. , If the secondary RPFs have been ruled out, and an idiopathic/autoimmune etiology is most likely, a trial of glucocorticoids and/or other immunosuppressive treatments with temporizing urinary drainage with indwelling ureteral stents or nephrostomy tubes have been studied. Medical treatment is particularly considered in mild to moderate obstruction. First-line medical treatment is prednisone with an initial dose of 0.75 to 1 mg/kg/day with a gradual taper to 5 to 7.5 mg/day within 6 to 9 months. Addition of immunosuppressive agents such as mycophenolate mofetil and cyclophosphamide may also be considered. Some studies have suggested that tissue diagnosis of the RPF should be performed in order to guide treatment. Some diseases such as lymphoma may mimic RPF. In the scenarios in which tissue diagnosis is warranted, surgical excisional biopsy should be performed concurrently with ureterolysis.
Patient positioning and trocar placement
For unilateral ureterolysis, the patient should be in semilateral decubitus (like that of a robotic nephrectomy) with modified low lithotomy, particularly for urethral access in female patients. All four arms of the da Vinci Xi system are used, in addition to one 5- or 10-mm bedside assistant trocar. All trocars except the most caudal one should be equidistant away from the vertical midline, approximately 2 to 3 cm on the ipsilateral side. The caudal-most trocar for retraction should be further medial right at midline. Seen in Fig. 33.2 .
For bilateral ureterolysis, the patient is positioned supine with low-modified lithotomy. The setup is almost identical to that of a robotic retroperitoneal lymph node dissection, except for the low modified lithotomy, with all ports along the Pfannenstiel line, as seen in Fig. 33.3 .
Technique
Ureteral identification and dissection have been discussed above. After the adventitia of the ureter has been identified, ureterolysis should be done in a systematic fashion by peeling back the anterior tissue, then exposing circumferentially to free the ureter from its posterior fibrosis. Using a vessel loop after the posterior has been freed is helpful to provide soft traction anteriorly to continue ureterolysis proximally and distally until normal periureteral fat is encountered. The fibrotic rind usually is not difficult to peel off the ureter once the correct plane has been established. Potts scissors for finer dissection may be helpful.
After the ureterolysis, a biopsy of the periureteral tissues and retroperitoneal mass should be sent off for pathologic evaluation. The ureter should then be assessed for its perfusion and can be done with intravenous ICG. If after ureterolysis, the tissue does not perfuse well, it may be necessary to excise the segment and perform ureteroureterostomy or other techniques, such as buccal graft ureteroplasty as described later in the chapter.
An omental wrap is then performed. A healthy omentum encasing the entire length of the ureter is used to prevent the recurrence of ureteral obstruction from its surrounding fibrotic tissues. The distal edge of the omentum is bifurcated. Enough should be mobilized to wrap the entire length of the ureter, and if more length is needed, the short gastric vessels can be ligated, freeing the omentum from the stomach. Care must be taken to preserve the left and right gastroepiploic arteries. If there is inadequate omentum, peritonealizing the ureter can be performed, although not preferred. The idea is to anteriorly displace the ureter and keep it out of the fibrotic retroperitoneum by tacking the peritoneal attachments of the colon underneath the ureter to the side wall. This technique does not provide the additional vascularity to the ureter as omental wraps do, and thus it is the opinion of the authors that it should be used as a last resort.
Ureteroneocystostomy (ureteral reimplantation)
Distal ureteral strictures may be managed with ureteral reimplantation. The goal is to exclude the strictured segment of the ureter by accessing a healthy ureter proximally and creating a new ureterovesical junction. Bladder tissue is well vascularized and allows for adequate perfusion for anastomotic healing. Robotic ureteroneocystostomy has been shown to have similar outcomes to open surgery but with the benefits of minimally invasive surgery: decreased postoperative narcotic use and shorter length of stay.
Patient positioning and robotic trocar placement
Male patients can be positioned supine on the operating room table whereas female patients may require low/modified lithotomy for urethral access. Urethral access is important for urethral catheter placement and removal, as it is important to instill fluid into the finished ureteroneocystostomy to test for watertight closure, and also important if ureteroscopy needs to be performed.
All four arms of the da Vinci Xi robot are used, in addition to one 5 mm bedside assistant trocar. The camera port should be supraumbilical. The two working arms should be several centimeters lateral to the camera port, with the contralateral working arm being a few centimeters more caudal. The retracting fourth arm trocar, as mentioned above, is contralateral to the diseased ureter of concern and even more caudal than the contralateral working arm, so that it is relatively close to the anterior superior iliac spine (ASIS) with enough distance away (usually just a couple centimeters) to not be restricted when moving the arm. The 5 mm assistant trocar should be a few centimeters cephalad to the midway point between the ipsilateral working trocar and camera trocar ( Fig. 33.4 ). It is recommended that all trocars be placed under direct visualization.
After all robotic trocars are placed, the operating table should be tilted to moderate-to-steep Trendelenburg position to allow the bowel to fall cephalad.
Technique
After the strictured distal ureteral segment has been identified, it is traced proximally until a healthy ureter is seen, where the ureter is then transected. The dissection of this transected ureteral stump is generally circumferential in order to give it mobility for reimplantation to the dome of the bladder. Newer techniques have been utilized, as will be discussed later in this chapter, for a nontransecting ureteral reimplantation that minimizes dissection in order to preserve ureteral blood supply. After the transected ureteral stump is mobilized enough to reach the dome of the bladder, which usually requires mobilization of the anterior aspect of the bladder off the pelvic and lower abdominal wall, the bladder is filled with approximately 300 mL of normal saline. The ureter is then spatulated approximately 2 to 3 cm and anastomosed to the cystotomy created about the same size, ensuring mucosa to mucosa apposition. An indwelling ureteral stent should be left prior to the completion of the anastomosis. Postoperatively, the Foley catheter is left between 7 to 10 days and the ureteral stent 4 to 6 weeks.
Psoas hitch
The psoas hitch is an adjunctive technique for mobility to make up length to facilitate more proximal ureteral reimplantations, but also a technique that takes tension off the anastomosis.
After the space of Retzius is developed, and adequate bladder mobility is achieved, an absorbable suture is used to tack the posterolateral aspect of the bladder to the ipsilateral psoas fascia. Both smooth and barbed absorbable sutures may be used. When suturing the psoas fascia, it is important to take the bite longitudinal to the fascial fibers; this reduces the risk of catching the genitofemoral nerve, which runs along the anterior surface of the psoas muscle. For strength, the psoas hitch suture can be thrown a few times before tying down.
Boari flap
A Boari flap should be considered as an adjunctive maneuver for more mobility when it is not possible to create a tension-free ureter-to-bladder anastomosis, even with the bladder mobilized and hitched to the ipsilateral psoas fascia. This may be seen in iatrogenic mid- to distal-ureteral strictures occurring from pelvic radiation, RPF, or other surgical interventions causing scarring. The robotic modality for Boari flaps has been shown to have enhanced outcomes. For all patients in whom a Boari flap reconstruction is being considered, the patient’s bladder capacity and compliance should be tested to be within normal or tolerable limits preoperatively with cystogram or urodynamics. In patients with poor capacity and/or compliance, a Boari flap may cause significant urinary frequency, urgency, and other symptoms secondary to decreased bladder volume, as the effective intraluminal bladder volume is decreased due to the elongated reconfiguration. Aside from these significant quality-of-life measures, patients with preexisting low bladder capacity and/or compliance may have increased filling and/or voiding pressures, predisposing the patient to vesicoureteral reflux in either nontunneled or tunneled reconstructions. From a technical standpoint, a patient with a baseline small bladder volume may not have enough tissue to be able to accommodate a tension-free ureteroneocystostomy anyhow. Thus, in patients with preoperative testing showing low capacity and/or compliance, other types of reconstructive methods may be better suited to achieve the safest and most favorable outcomes.
Patient positioning and robotic trocar placement
Positioning is similar to that of a non-Boari flap ureteral reimplantation.
The trocar placement is also similar to that of unilateral non-Boari flap ureteral reimplantation, with all ports a few centimeters more cephalad. How much more cephalad the trocars are placed depends on how proximal the stricture is.
Technique
After the ureter has been transected proximal to the diseased segment, the bladder adequately mobilized, and a psoas hitch performed, the Boari flap creation may be started. The bladder is first filled with 300 to 500 mL of normal saline. The flap is then scored over the bladder serosa with electrocautery. A flap length of up to 10 to 15-cm can be developed if bladder capacity is adequate. The shape is an inverted “U” with the base being wider than the apex. The apex of the flap will become the proximal aspect that is anastomosed to the ureter after its construction. It is important that the base of the inverted “U,” which corresponds to the junction between the bladder and the Boari flap, is wide in order to minimize the risk of flap ischemia, often described to be at a minimum of 4 cm in width.
After scoring the bladder serosa, the flap is then cut transmurally. Sharp cutting is preferred in order to retain the bladder’s intrinsic vascularity, but minimal electrocautery may be used for hemostasis. The apex of the flap is then brought up to the ureteral stump. For additional measures to take off tension, the posterior aspect of the flap may be tacked to the psoas fascia similar to that of the psoas hitch as described above. The ureter should be spatulated posteriorly about 1.5 to 2.0 cm. After that is done, the posterior plate of the ureter-Boari flap anastomosis is created by absorbable 4-0 suture, taking the apex of the Boari flap to the crotch of the posterior ureteral spatulation ( Fig. 33.5 ). Once the posterior plate is completed, ensuring adequate mucosa-to-mucosa apposition, an indwelling ureteral stent is placed. The anterior aspect can then be completed with 4-0 absorbable suture by anastomosing the anterior ureter to the flap, which is wrapped around the stent to create the lumen ( Fig. 33.6 ). This is a refluxing anastomosis.
